You'd be much better off asking this on one of the HK sites focussed on expats living here. For example http://www.geoexpat.com/forum/

FWIW HKIS is a Christian Missionary school that rejects well-qualified teachers who apply for posts there simply on the grounds that they are not Christians. For me that's enough in itself for me not to want any kids of mine to go there. YMMV